Device for delivering a surgical implant

ABSTRACT

A device ( 10 ) for delivering a surgical implant ( 14 ) comprises a guide track ( 11 ) for guiding the movement of a spinal implant ( 14 ) to an implantation site. An implant carrier ( 12 ) engages the implant in the guide track and can move along the guide track in order to deliver the implant to the implantation site, the carrier ( 12 ) including a connector ( 15 ) which can be displaced between a connected position in which the implant is connected to the carrier to move with it in the guide track, and a disconnected position in which the implant can be separated from the carrier. A driving device ( 13 ) can engage the implant carrier to move the carrier ( 12 ) along the track. A formation can cause the connector ( 15 ) on the implant carrier ( 12 ) to be displaced from the connected to the disconnected position when the carrier reaches a pre-determined position.

This invention relates to a device for delivering a surgical implant.

Interbody spinal implants are fitted between vertebrae to stabilise thevertebrae. An implant can be implanted as a disk replacement. An implantcan be used in fusion of the vertebrae.

A known spinal implant is disclosed in WO-A-01/06962. It comprises acage made from a shape memory alloy. It is introduced into the spacebetween two vertebrae through a minimal access opening (posteriorapproach).

Ease of manipulation of the implant is a very important requirement;also a highly desirable feature of an implantation device is tofacilitate easy cleansing and sterilisation after use, given that bodyfluids can easily enter the interior of any device used for spinalimplantation.

In one aspect, the present invention provides a device for delivering asurgical implant, which comprises:

a guide track for guiding the movement of a spinal implant to animplantation site of a patient;

an implant carrier for engaging an implant in the guide track and whichcan move along the guide track in order to deliver the implant to theimplantation site, the carrier including a displaceable connector whichcan be displaced between a connected position in which the implant isconnected to the carrier to move with it in the guide track, and adisconnected position in which the implant can be separated from thecarrier;

a driving device which can engage the implant carrier to move thecarrier and an implant which engages the carrier along the track; and

a formation which causes the displaceable connector on the implantcarrier to be displaced from the connected position to the disconnectedposition when the carrier reaches a pre-determined position relative tothe guide track, to allow the implant to be released from the device forimplantation.

The invention therefore enables easy guidance of an implant to animplantation site and, upon release of the implant, the surgeon may thenmanually complete the implantation. When, as is preferred, the implantis formed from a shape memory alloy, it can revert from a deformedconfiguration in which it is held within the guide track to an in-useconfiguration, especially involving straightening of the implant.

Preferably, the connector is pivotably connected to the implant carrier.The connector can then be displaced from the connected position to thedisconnected position by pivoting. Other displacements are envisaged.For example, the connector might be displaced sliding or translating.

Preferably, the driving device is a manually operative device andconveniently advancing and reversing movement of the elongate carriercan be carried out by manipulation of finger-operated levers.

Preferably, the formation comprises a ramp. The ramp can be inclined tothe guide track.

Preferably, the formation comprises an recess into which the connectorcan be displaced, for example by pivoting. Preferably the opening (forexample with an associated ramp) is provided in the bottom face of theguide track so that the formation can drop into the opening whenpositioned adjacent thereto.

In a preferred arrangement, the implant carrier takes the form of atoothed rack, and the driving device may include a ratchet-type of drivepin or the like to engage intermittently with the rack, and therebycause incremental advance or return movement of the rack as required.However, other drive connections may be provided between the drivingdevice and the toothed rack, including a drive pinion.

Preferably, the guide track is in the form of a channel in which theimplant can slide. The channel is preferably at least partially enclosedso that the implant can be discharged from the channel at or towards oneend, and not through the top or bottom of the track. The guide track canbe generally C-shaped when viewed in cross-section, especially where theopen side of the “C” is directed upwardly so that the re-entrantportions prevent the implant from being removed from within the trackthrough the top thereof.

The track should be dimensioned so that the implant is a sliding fitwithin it. The track will generally have a constant cross-section alongits length. When the implant is a spinal implant to be fitted betweentwo vertebrae, its depth will generally in the range 4 to 8 mm.Accordingly, the width of the track is preferably at least about 4 mm,more preferably at least about 8 mm. The width of the track will oftenbe not more than about 15 mm, especially not more than about 12 mm. Thethickness of a spinal implant will generally be in the range 0.5 to 1.5mm. The depth of the track is preferably at least about 0.5 mm, morepreferably at least about 1.0 mm, for example at least about 1.5 mm.

The implant and the connector can be connected by means of interfittingplug and recess. The recess will often have a reentrant shape so thatthe plug can only be fitted into it by sliding it in a direction whichis not aligned with the direction in which the implant moves in theguide track, often generally perpendicular to that direction. Suitablereentrant shapes are often referred to as dove-tail shapes, although itwill be understood that the recess which is used in the presentinvention can be rounded or angular. Accordingly, it can be preferredfor one of the implant and the connector on the carrier to have adove-tail shape at its end, and the other to have a recess in which thedove-tail shape can be received.

Preferably, the driving device has a housing in which the drivingcomponents are housed, and the housing may be separable into at leasttwo separate portions to allow easy access to the interior for thepurposes of cleaning/sterilisation of the internal components, and theinterior of the housing, after surgery. Preferably, the driving deviceincludes at least one driver lever for causing movement of the implantcarrier in the guide track.

Embodiments of devices according to the invention will now be described,by way of example, with reference to the accompanying drawings, inwhich:

FIGS. 1 a, b, c and d are separate views of, respectively, the implantcarrier, the implant, the implant coupled to one end of the implantcarrier, and a pivoted release arrangement at one end of the implantcarrier for effecting release of the carrier after the latter has beendelivered to the implantation site.

FIG. 1 is a perspective view from one side of a manually operativedriving device, guide track, and implant carrier, in non-assembled form,and forming a spinal implantation device according to the invention foruse in delivering a spinal implant to an implantation site of a patient;

FIG. 2 is a perspective view, from an opposite side of the housing ofthe driving device, showing manually operative levers for applyingadvancing and reversing movement to the implant carrier;

FIG. 3 is a perspective illustration, partly in plan view, showing inmore detail, the mounting on the driving device on which the guide trackand implant carrier can be mounted; and

Referring now to the drawings, a spinal implantation device according tothe invention is designated generally by reference 10 and comprises aguide track 11 for guiding the movement of the spinal implant to animplantation site of a patient, and an elongate implant carrier 12 whichis moveable lengthwise of the guide track 11 in order to deliver theimplant to the implantation site, and a driving device 13 which isengageable with the elongate carrier 12 and operative to apply indexingmovement to the carrier.

FIG. 1 shows separate views of the implant carrier 12, and an implant14, and how they work together in order to deliver the implant to therequired patient site and then effect release of the implant for finalcompletion of the implantation process.

FIG. 1 c shows the implant 14 coupled to a leading end of the implantcarrier 12 and FIG. 1 d shows the implant after release from thecarrier, when it has been delivered to the implantation site. There isshown schematically a pivotable element 15, which in the illustratedarrangement is connected to the leading end of the carrier 12 and whichengages with the implant 14, when the latter has reached theimplantation site, so as to release the implant from the carrier 12 andallow completion of the implantation.

The invention therefore provides for easy guidance of the implant 14 tothe implantation site, and upon release of the implant, the surgeon maythen manually complete the implantation. When, as is preferred, andshown in FIG. 1 b, the implant is a curved shape memory cage, this mayeasily be manipulated so as to complete implantation.

FIG. 2 shows the guide track 30 which has a reentrant shape when viewedin cross section along its length defined by a base 32, side walls 34and top walls 36 which cover only the edges of the base 32. The width ofthe track is such that the implant carrier 12 is a close sliding fitbetween the side walls 34, and between the base 32 and the top walls 36.A part 35 of one of the side walls has been cut away in FIG. 2 to enableinternal features of the track to be seen.

The base 32 has an aperture 37 formed in it which extends across most ofthe width of the track and is large enough for the pivotable element 15on the implant carrier to be displaced into. The aperture can be open,or can be in the form of a recess which is closed at its base. This canbe preferred in order to control the extent of the displacement of thepivotable element.

Each of the top walls 36 has a ramp 38 formed in it, in the surfacewhich faces towards the base. The ramp is located at about one of theedges of the aperture. It has an inclined surface facing towards thebase of the track.

The width of the implant is less than the distance between the ramps 38(measured across the guide track) so that the implant can slide alongthe track past the ramps. The width of the pivotable element 15 isgreater than the distance between the ramps so that the pivotableelement is acted on by the ramps as it passes under the ramps. Thesewidth features are apparent from FIG. 1 c.

The action of the ramps on the pivotable element displaces the elementpivotally into the aperture 37. The nature of the connection between thepivotable element is such that the implant is released from the implantcarrier as a result of this displacement (as shown in FIG. 1 d). Afterthe implant has been released from the carrier, the carrier canwithdrawn along the guide track. The pivotable element 15 then resumesits aligned configuration which it adopted before displacement by theramps.

Referring to FIGS. 3 to 5, this shows some features of the constructionand operation of a manually operated driving device 13 in whichadvancing and reversing movement of the elongate carrier 12 is carriedout by manual manipulation of finger operated levers 16 and 17.

The implant carrier 12 preferably takes the form of a toothed rack, asshown, and the driving device 13 may include a ratchet-type of drive pin(not shown in detail) or the like, to engage intermittently with therack, and thereby cause incremental advance or return movement of therack as required. Suitable ratchet drive mechanisms can be devised basedon conventional mechanisms as used in various applications. Other driveconnections may be provided, to transmit linear reciprocating movementto the rack 12, including a drive pinion.

The driving device 13 has a two part housing in which the drivingcomponents are housed, and which may be separated, by operation of apush button 18, to allow easy access to the interior for the purposes ofcleansing/sterilising the internal components after surgery and also theinterior of the housing.

1. A device for delivering a surgical implant, which comprises: a guidetrack for guiding the movement of a spinal implant to an implantationsite of a patient; an implant carrier for engaging an implant in theguide track and which can move along the guide track in order to deliverthe implant to the implantation site, the carrier including adisplaceable connector which can be displaced between a connectedposition in which the implant is connected to the carrier to move withit in the guide track, and a disconnected position in which the implantcan be separated from the carrier; a driving device which can engage theimplant carrier to move the carrier and an implant which engages thecarrier along the track; and a formation which causes the displaceableconnector on the implant carrier to be displaced from the connectedposition to the disconnected position when the carrier reaches apre-determined position relative to the guide track, to allow theimplant to be released from the device for implantation.
 2. A device asclaimed in claim 1, in which the formation is located at or towards theend of the guide track from which the implant is delivered.
 3. A deviceas claimed in claim 1, in which the connector is pivotably connected tothe implant carrier.
 4. A device as claimed in claim 1, in which theguide track includes a recess in it into which the connector can bedisplaced to allow it to be disconnected from the implant.
 5. A deviceas claimed in claim 1, in which the formation comprises a ramp.
 6. Adevice as claimed in claim 1, in which the driving device is manuallyoperated.
 7. A device as claimed in claim 1, in which the implantcarrier comprises a toothed rack, and the driving device includes adrive pin or the like to engage with the rack.
 8. A device as claimed inclaim 1, in which the driving device includes a housing in which drivingcomponents are housed.
 9. A device as claimed in claim 7, in which thehousing is separable into at least two separate portions to allow accessto its interior for cleaning purposes.
 10. A device as claimed in claim1, in which the driving device includes at least one driver lever forcausing movement of the implant carrier in the guide track.
 11. Anassembly which comprises a device for delivering a surgical implant asclaimed in claim 1, and a surgical implant fitted within the guidetrack.
 12. An assembly as claimed in claim 11, in which the surgicalimplant is formed from a shape memory alloy.
 13. An assembly as claimedin claim 11, in which the surgical implant can revert from a deformedconfiguration which it adopts while in the guide track and an in-useconfiguration which it adopts once discharged from the guide track. 14.An assembly as claimed in claim 13, in which the configuration of theimplant when in use is curved and the configuration of the implant whendeformed for implantation is essentially straight.
 15. An assembly asclaimed in claim 11, in which the surgical implant is a spinal implantto be fitted between two vertebrae.
 16. An assembly as claimed in claim11, in which one of the implant and the connector on the carrier has adove-tail shape at its end, and the other has a recess in which thedove-tail shape can be received.